The disclosure relates to the field of the production of metal wires intended for the creation of tire reinforcements. In general, these wires are used to produce the reinforcing plies made up of lengths of wire coated in a rubber compound, parallel to one another, and making a given angle with the longitudinal direction of the ply.
These wires may be individual wires or assemblies of wires obtained by plying individual metal wires together.
To improve their strength, some of these wires, of the type of wires formed by assembly, have the particular feature of having a core coated with rubber. These wires are rubberized during their manufacture with rubber in the uncured state in order to improve their corrosion resistance and therefore their endurance notably in tire carcass reinforcements for industrial vehicles.
In the known way, these rubberized wires are subjected to significant stresses when the tires are being driven on, notably to bending or variations in curvature repetitively giving rise to friction in the wires which lead to wearing or fatigue of the wires. As a result, it is very important for these wires to be impregnated with rubber as much as possible and for the rubber to penetrate as well as possible into the spaces between the wires when several of these wires are assembled to form cords.
Typically, the wires are coated with a rubber compound coming from an extruder the outlet of which opens into a sheathing head comprising a sheathing die through which the wire or assembly of wires for coating passes. The operating parameters of the extruder are chosen in such a way as to ensure uniform coating of the wire or wires passing through the sheathing die.